Cut bread into 1-in.-thick slices. Arrange in a single layer in a greased 13x9-in. baking dish. Lightly beat next 6 ingredients; stir in milk and cream. Pour egg mixture over bread, turning once to coat. Refrigerate, covered, overnight.
Preheat oven to 375°. Turn bread again to coat. For topping, combine flour, brown sugar, butter, cinnamon and, if desired, nutmeg. Sprinkle flour mixture over bread.
Bake, uncovered, until a knife inserted in center comes out clean and topping is golden brown, 40-45 minutes. Let stand 10 minutes before cutting. Top with raspberries or blueberries; sprinkle with confectioners' sugar.
